#include <iostream>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string>
#include <cstring>
#include <cstdlib>
using namespace std;

#define N 2
#define NUM 1024

void Writer(int wfd)
{
    string s = "I am child";
    pid_t self = getpid();
    int number = 0;

    char buffer[NUM];
    while(true)
    {
        sleep(1);
        buffer[0] = 0;
        snprintf(buffer, sizeof(buffer), "%s-%d-%d", s.c_str(), self, number++);
        write(wfd, buffer, strlen(buffer));
    }
}

void Reader(int rfd)
{
    char buffer[NUM];
    int cnt = 0;
    while(true)
    {
        buffer[0] = 0; 
        // system call
        ssize_t n = read(rfd, buffer, sizeof(buffer)); //sizeof != strlen
        if(n > 0)
        {
            buffer[n] = 0; // 0 == '\0'
            cout << "father get a message[" << getpid() << "]# " << buffer << endl;
        }
        else if(n == 0) 
        {
            printf("father read file done!\n");
            break;
        }
        else break;

        cnt++;
        if(cnt>5) break;
    }
}

int main()
{
    int pipefd[N] = {0};
    int n = pipe(pipefd);
    if(n < 0)
    {
        return 1;
    }

    pid_t id = fork();
    if(id < 0)
    {
        return 2;
    }
    if(id == 0)
    {
        close(pipefd[0]);
        Writer(pipefd[1]);
        close(pipefd[1]);
        exit(0);
    }
    close(pipefd[1]);
    Reader(pipefd[0]);
    close(pipefd[0]);
    cout << "father close read fd: " << pipefd[0] << endl;
    sleep(5);

    int status = 0;
    pid_t ret = waitpid(id, &status, 0);
    if(ret < 0)
    {
        return 3;
    }

    cout << "wait child success: " << ret << " exit code: " << WEXITSTATUS(status) << " exit signal: " << WTERMSIG(status) << endl; 
    sleep(5);
    cout << "father quit" << endl;
    return 0;
}